Relative Minus Sign for u d -> u d Process?

In summary, the conversation is about the process of u d -> u d and the use of full SM. The question is whether there is a minus sign between the process with W and the process with γ. The answer is yes, based on information that explains the reason for the minus sign.
  • #1
dimitronic
2
0
relative minus sign??

Hi, I have one question for you...
to compute the matrix element for the process u d -> u d I want to use full SM, but I have one problem I'll give you the maths.


process with W:
<ud|(\bar{Ψ}u Ψd)(\bar{Ψ}dΨu)|ud>
process with γ:
<ud|(\bar{Ψ}u Ψu)(\bar{Ψ}dΨd)|ud>
Z and g are the same with γ (i don't write the propagators and the Lorentz parts for simplicity).
Is there a minus sign between W and the others??
I say yes ... but i am not sure.
 
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  • #2
I just posted this for another post... I SAY YES also.
here's the information I found that explains why there is a minus sign.

rel min sign.jpg
 

1. What is the significance of the relative minus sign in the u d -> u d process?

The relative minus sign in this process signifies the direction of charge flow. In this case, the minus sign indicates that the charge is flowing from the initial state (u d) to the final state (u d).

2. How is the relative minus sign determined in the u d -> u d process?

The relative minus sign is determined by the conservation of charge, which is a fundamental law in particle interactions. It is based on the charge of the initial and final states, and the direction of charge flow.

3. Can the relative minus sign change in the u d -> u d process?

No, the relative minus sign cannot change in this process as it is determined by the initial and final states and the direction of charge flow. However, in other processes, the relative minus sign can change depending on the charge of the initial and final states.

4. What is the role of the relative minus sign in the cross-section calculation for the u d -> u d process?

The relative minus sign is crucial in the cross-section calculation for the u d -> u d process as it affects the overall sign of the amplitude. This sign is then squared to calculate the probability of the process occurring, making it a crucial factor in the calculation.

5. How does the relative minus sign affect the overall interpretation of the u d -> u d process?

The relative minus sign plays a significant role in the interpretation of this process as it determines the direction of charge flow and the overall sign of the amplitude. It also helps in understanding the conservation of charge and its importance in particle interactions.

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